/*
 * Alloy Analyzer
 * Copyright (c) 2002 Massachusetts Institute of Technology
 *
 * The Alloy Analyzer is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * The Alloy Analyzer is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with the Alloy Analyzer; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package alloy.transform;

import alloy.ast.ASTDepthFirstVisitor;
import alloy.ast.EmptyFormula;
import alloy.ast.Formulas;
import alloy.ast.Leaf;
import alloy.ast.Node;

/** Perform miscellaneous simplifications. */
public class SimplifyVisitor extends ASTDepthFirstVisitor {
    /** If the {@link Formulas} node is empty, it means a constant-true formula.
	Ensure that only {@link Leaf} nodes can be leaves of the AST
	by replacing empty {@link Formulas} nodes with an {@link EmptyFormula}
	which is a {@link Leaf}. */
    public void visit(Formulas formulas_) {
	if (formulas_.numChildren() == 0) {
	    formulas_.addFormula(new EmptyFormula());
	    //Dbg.warn("generated an empty formula");
        } else {
            visit((Node)formulas_);
        }
    }
}
